Apparatus for controlling movement of flowable particulate material

ABSTRACT

The present invention is directed toward various valving arrangements to control the flow of granular material. In one embodiment, a valve is provided which facilitates flow of the material in one direction, but resists flow in another direction. In another embodiment, a retaining wall is provided with a plurality of generally horizontal passageways, which, under normal circumstances, resist passage of the flowable granular material positioned therebehind and, under modified circumstances, can serve as relief valves to avoid pressure on the wall which might cause the wall to move in an undesirable manner. In a third embodiment, a plurality of valving units is provided for beach retention of sand through efficient separation of sand from incoming waves.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus for controlling movement offlowable granular material in such a manner as to provide efficientvalves therefor, along with specific end uses such as retaining wallsand for beach renourishment.

2. Description of the Prior Art

It has been known for various purposes to control the movement offlowable granular materials through various mechanical devices, underthe influence of gravity or other forces and through various forms ofpumping systems.

It has also been known to attempt to resist loss of sand in beachesunder the influence of open water waves which tend to apply a forcecausing particles of sand to become entrained in water and carried awayfrom the beach. For example, various types of physical barriers such aswalls, as well as the use of stabilizing plant life and physical objectspositioned on beaches, have been employed in an effort to resistundesired erosion.

SUMMARY OF THE INVENTION

The present invention contains several embodiments of flowable granularmaterial control systems. In one embodiment, a valve which can permitfree flow and movement of the material in a first direction, but resistssuch flow in a second direction is provided. In another embodiment, aretaining wall which under normal circumstances serves to retain aformation of flowable granular material is provided. The retaining wallmay be provided with a plurality of elongated passageways such that asthe angle of repose under normal circumstances will resist undesiredflow of the material through the passageways. These passageways may beso provided in number and size as to permit flow therethrough undermodified conditions to thereby minimize the likelihood of the wall beingtoppled by a force imposed by the retained flowable granular material.They also facilitate passage of some of the material through saidpassageways to thereby resist major landslides.

In a further embodiment of the invention, a beach retention systemhaving a plurality of individual units provided with wave deflectionramps with generally horizontal openings which receive the watercontaining sand thereover and a plurality of spaced interior barrierplates which receive deposited sand therebetween and have interiorhorizontal slots for the vertical transfer of sand downwardly and ananchor portion securing the units within sand. The anchors may havevalve openings for discharge of drained water after sand is separatedtherefrom.

It is an object of the present invention to provide improved valveswhich do not require moving parts and serve to control flow of flowablegranular material.

It is yet another object of the present invention to provideapplications for such valves which permit flow of the granular materialin a first direction while resisting such flow in the oppositedirection.

It is another object of the present invention to provide for enhancedstability of structures containing or composed of flowable granularmaterial and for the use in retaining walls having a plurality ofpassageways which are so positioned and sized as to resist passage offlowable granular material therethrough under normal circumstances andfacilitate such passage under unusual circumstances.

It is yet another object of the present invention to provide aneffective means for retaining sand on beaches through appropriatecontrol of the flow of incoming water which contains suspended sand.

These and other objects of the invention will be fully understood fromthe following description of the invention with reference to thedrawings appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a valve of an embodiment of thepresent invention.

FIG. 2 is a series of pairs of schematic illustrations ofone-directional flow valves of the present invention.

FIG. 3 is a front elevational view of a retaining wall of the presentinvention disposed adjacent to a pile of flowable granular material.

FIG. 4 is a cross-sectional illustration of the retaining wall andadjacent flowable granular material taken through 4-4 of FIG. 3.

FIG. 5 is a schematic elevational view of a form of beach erosioncontrol system of the present invention.

FIG. 6 is an illustration of a wave deflection ramp which forms aportion of a unit of the beach erosion control system.

FIG. 7 is an elevational view showing portions of two vertically spacedunits of the beach erosion control system.

FIG. 8 is a fragmentary illustration showing valve action on portions ofthe beach erosion control system.

FIG. 9 is a partially schematic view of a portion of the beach erosioncontrol system showing a plurality of units which are vertically spacedfrom each other.

FIG. 10 is an elevational view showing an anchor portion of two units.

FIG. 11 is a cross-sectional view taken through 11-11 of FIG. 5.

FIG. 12 is a cross-sectional view taken through 12-12 of FIG. 5.

FIG. 13 is a top plan view of the embodiment of FIGS. 5 through 12generally, but showing four additional elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present inventor's U.S. Pat. No. 6,739,827 contains disclosures ofmethods and apparatus for movement of an article employing flowableparticulate matter and also contains disclosure of valves suitable fordischarging such flowable granular material. The disclosure of thispatent is expressly incorporated herein by reference.

As employed herein, the term “earth” is employed in generallyconventional sense to mean the fragmental material comprising part ofthe land portion of the globe. It is sometimes referred to in generalusage as “soil” or “dirt”.

As employed herein, the term “flowable granular material” means aplurality of solid particles which, under the influence of gravity andother forces, will be subject to relative movement with respect to othersuch particles and shall expressly include, but not be limited to, sand,earth, soil, bulk grains, rock particles, synthetic particles andcombinations thereof. The particles or granules may be considered tohave “semi-hydraulic” properties.

As employed herein, the terms “angle of repose” shall refer to the anglethat the upper surface of a pile of flowable granular material, such assand, forms with respect to the horizontal naturally when piled on aflat surface. The angle defines the magnitude of the horizontal forcethat the sand, for example, exerts when piled against a generallyvertical surface. Such angles of repose are frequently about 20 to 46°.

Rankine in Rankine, J. B. (1857), “On the Stability of Loose Earth”,Philosophical Transactions of the Royal Society of London, Volume 147,Part 1, Pages 9-27, provided guidance regarding the determination of astable angle of repose for loose earth under the influence of a uniformforce such as gravity. The horizontal force perpendicular to a verticalplane with flowable “earth” is calculated by Rankine to be inverselyrelated to the angle of repose. It increases as the angle of reposedecreases. As the angle of repose decreases, the bottom edge of the“earth” moves “outward”.

Referring to FIG. 1, there is shown a valve opening 2 which is definedby an upper passageway-defining surface 4, a lower passageway-definingsurface 6 and a pair of lateral passageway surfaces 8, 10 extendingtherebetween. The valve opening 2 is defined within a structure 12 whichmay be composed of any suitable material such as stone, concrete, metal,organic materials, such as wood, plastic and combinations thereof.

Referring to FIG. 2, there are shown three pairs of views of threevalves such as a1-a2, b1-b2 and c1-c2. These involve an extension of aprinciple shown within FIGS. 3 and 4 of U.S. Pat. No. 6,739,827. In thisembodiment, movement of the flowable granular material through the valvepassageway in a first direction is readily permitted, while it isresisted in the opposite second direction. The flow of the granularmaterial as shown in Figures a1 and a2, which represent sand valveswithout movable parts is freely permitted in the direction of arrow A asshown in Figure a2, but is resisted in a second direction as shown byarrow B. The particulate material 14 in the valve shown in Figure a2readily flows in the first direction A under the influence of a forcevector such as, for example, gravity or centrifugal (downward as drawnrotational) force between upper passageway-defining surface 4 and lowerpassageway-defining surface 6. By contrast, the flowable material 16 asshown in Figure a1 is resisted in second direction B. In the form shown,both the upper passageway-defining surface 4 and the lowerpassageway-defining surface 6, as well as lateral connecting passagewaysurface 8 and 10 are generally planar. The included angle X between thegenerally planar passageway-defining surfaces 4, 6 is maybe about 10 to55° and preferably about 20 to 45°. It will be appreciated that theplanar surfaces 4, 6, 8 and 10 may be provided with irregular shapes orcurved shapes, if desired, so long as the angle of repose X facilitatesthe one-way flow concepts of this embodiment of the invention.

Similarly, with respect to the valve shown in b1, b2, the position ofthe upper and lower passageway-defining surfaces which have been labeled24 and 26 in these figures is inverted with respect to Figures a1 anda2. With this reversal, it will be seen that the flowable material 30 inFigure b1 moves readily under the influence of gravity or centrifugalforce, as desired, through the valve in the first direction C, while theflow of the granular material 32 in a second direction D is resisted. Itwill be appreciated that the repose angle Y may be about 10 to 90° andpreferably about 20 to 45° depending on the granular material involved.

The embodiment shown in Figures c1, c2 shows an upper valve element 40having a generally planar passageway-defining surface 42 and a lowervalve element 44 having a generally flat passageway-defining surface 46.It will be appreciated that in this embodiment the width W of uppervalve element 40 is greater than the width w of lower valve element 44.Flow of the flowable granular material 56 in a first direction E isresisted because the granular angle of repose is greater than the designvalue. Flow of flowable granular materials 54 in the direction F isachieved as a result of the angle of repose Z¹ being less than thedesign value thereby permitting flow in such direction of selectedflowable granular materials. This shows an angle of repose Z which isabout 10 to 50° and preferably about 20 to 45°. In this embodiment,granular material flow in the directions opposite arrows E and F isresisted.

It will be noted in connection with Figure c1 and c2 that an angle ofrepose greater than the repose angle Z is subjected to blocking of thematerial 50 by valve element 40. The portion of flowable granularmaterial with an angle less than the angle of repose Z¹ will passthrough the valve as shown in Figure c2. In this embodiment, the upperand lower surfaces may be generally horizontal with the difference inwidths W, w providing the desired valve action.

Another embodiment of the invention which centers around providing animproved safer retaining wall for flowable granular material. As statedhereinbefore, as the angle of repose of a flowable granular materialdecreases, the horizontal force within the material increases. Theflowable granular material, such as earth, for example, under theinfluence of such changes can change from a cohesive fragmental materialcapable of stability, when formed, for example, as an exposed verticalsurface, to an unstable “flowable” material by imposition of amechanical or acoustic shock, or pressure, or by the addition of, orsubtraction of aqueous moisture or that of other fluids within thematerial or a segment or layer of the material. This can lead tolandslides or the collapse of the “earth” wall of an excavation. Solidretaining walls are often employed to resist such failures. When such alandslide or collapse occurs, the earth (or a strata thereof)reconfigures itself in a suitable angle of repose which resists furthermovement of the “earth”. With present retaining wall design, theincreased horizontal Rankine force on the retaining wall structure, asthe internal Rankine angle changes, can destroy the structure andendanger the objects or personnel protected by the wall.

In the embodiment of the present invention illustrated in FIGS. 3 and 4,the change that makes the “wall” or a segment or strata of the “wall”unstable causes the now flowable granular material to pass into orfurther through one or a series of “valves” as described hereinbefore inconnection with FIGS. 1 and 2. The contained sloped flowable granularmaterial segments in the vertical series of such valves restrains thefurther flow of the collapsing “wall” without adding large furtherdestructive horizontal force to the improved retaining wall structure.This enhances the safety of protected objects or personnel beyond theretaining wall. If the change in earth structure is such that it resultsin a final angle of repose less than that contained by the design of theretaining wall valve segments, the flow of “earth” passes through thevalves. This warns observers of the change in earth dynamics whileallowing the basic retaining wall to remain in place. There is shown inFIGS. 3 and 4 a retaining wall 70, which may be composed of any suitablematerial such as stone, concrete, metal, organic materials, such aswood, plastic and combinations thereof. The wall 70 is generallyvertically oriented and has a front face 72 and a rear face 74. It issupported adjacent to a surface 76 being protected by the retaining wall70. Adjacent the rear face 74 is disposed a mound 80 which is or maybecome a flowable granular material which slopes toward the wall 70. Aprime purpose of the wall 70 is to resist undesired flow of the material80 onto the surface 76. The wall 70 must also resist forces applied tothe rear surface 74 by the material 80. The angle of repose of thematerial being retained is of importance in this context. For example,when the moisture content of the retained flowable granular material 80increases, it can become flowable granular material. When this occurs,the angle of repose generally decreases and the force attempted to urgethe wall in the direction of surface 76 increases. A prior approach tohandling such a problem is to make the retaining wall 70 overly strongand, therefore, increase the expenses of the same substantially. Inspite of this, failures do occur, particularly with certain types ofsoils whose flow properties and compaction may change abruptly withmoisture content or mechanical vibration such as occurs during anearthquake.

The present design resists such undesired failure of a wall by providinga plurality of elongated horizontal passageways such as 88, 90 and 92which are provided with a horizontal extent having a ratio to thevertical extent of about 3 to 1 and preferably greater than about 1 to 1of each said opening 88, 90, 92 dependent on the nature of the flowablegranular material. While the range may vary depending upon designpreferences, it is preferred that about 70 to 90% of the exposed wallrear surface be occupied by the elongated horizontal passageways. In theform shown, a top row of passageways 88, 90, 92 overlies an intermediaterow 94, 96, 98, which, in turn, overlies a row 100, 102, 104. It ispreferred that the angle of repose of the flowable granular materialwithin the passageways 88-104 (even numbers only) be such that thematerial extends only to adjacent the front surface 72 of the wall 70without spilling over. It is preferred that the base surface of eachhorizontal passageway such as surface 110 of passageway 92 or surface112 of passageway 90 be substantially planar and be horizontallyoriented.

The retaining wall 70 will withstand the full horizontal stress of theflowable granular being retained. If, for example, increased moisturecontent or an earthquake causes the flowable granular material to changeso that increased horizontal force would be exerted against theretaining wall 70, then the angle of repose becomes less. The greaterforce is relieved by the flowable granular material sliding furtherthrough or out of the passageways 88-104 (even numbers only). Thisserves to provide a safety valve-type effect by automatically lesseningthe force applied to the rear surface 74 of the retaining wall, the wallcontinuing to remain in place and provide the desired protection.

It would be appreciated that the retaining wall 70 uses less material toachieve the desired retention capability than that of the prior art.This is due to the fact that there is automatic “over-pressure” orsafety relief.

Referring now to FIGS. 5 through 13, an embodiment of the inventionwhich is designed to employ certain sand valve concepts of the presentinvention along with horizontal slots for delivering flowable granularmaterial, such as sand, and anchoring elements. The system is structuredto be secured within a body of water which has fluid in motion, such asopen water, which has waves moving toward a sloping shore surface. Oneof the problems encountered with such beach areas and the like is thatthe force of the waves tends to entrain the flowable granular material,such as sand, and transport it away from the beach or land area, therebycreating undesired erosion problems. The system of this embodiment isdesigned to recapture the flowable granular material and restore it inthe beach or shore area, thereby resisting undesired beach erosion.

A second aspect of this embodiment is the ability to use the system toprotect a “submerged beach” such as the edge of a channel leading into afresh or salt water port.

In general, the apparatus is structured to avoid substantial impeding ofthe force of a water wave approaching the beach, while extracting aportion of the flowable granular particles such as sand contained withina wave and then to inhibit the return of the extracted sand to openwater as the water wave recedes from the beach.

It will be appreciated that the structure to be described herein may beof any desired length or width depending upon the physical environmentand objectives of the user. Also, the structure is preferably applied ina plurality of vertically spaced units and a greater or lesser number ofunits may be provided dependent upon the physical environment in whichthey are placed and the objectives of the user. It is also desired totrap the sand or other flowable granular materials in such a manner asto maintain the normal angle of repose of the sand on that beach.Further, as will be described herein, the individual units are anchoredto the beach and have structures to permit return of excess fluids suchas water to the main body.

The flowable granular particles removed from a wave are either storedwithin the unit in which they are trapped or moved downwardly to a lowerlevel within the structure and deposited on the beach. In FIG. 5, thereis shown a plurality of beach stabilizing units 120, 124, 126, 128, 131which have the right ends, respectively 130, 132, 134, 136, 138,positioned closest to an approaching wave which arrives moving in thedirection shown by arrow G and the opposing ends closer to the beach orshore. It will be noted that in the preferred embodiment a step-likearrangement of the units is provided. As shown in FIG. 5, units 128 and130 have their outer ends farther from the beach than units 124, which,in turn, has its outermost end closer to the beach than unit 126, butfarther from the beach than unit 120. Referring to the uppermost unit120, it has a ballast portion 140 which has an inwardly and upwardlysloped ramp 142 over which the waves will flow. It is preferred that theupwardly sloped ramps be substantially continuous to facilitateefficient flow thereover. It also has a generally vertical rear wall 144within which sand passing over surface 142 may be deposited such as 148on generally horizontal surface 150. A plurality of elongatedhorizontally oriented slots 160, 162, 164 serves to permit sand to passtherethrough and under the influence of gravity and external waveaction. The sand drops to the region 166 underlying unit 120 andoverlying unit 124 to be captured on the horizontal surface 172 of unit124 with a portion of the flowable material passing through elongatedhorizontal slots 174, 176, 178 to drop onto portions of unit 126. Unit124 has a plurality of vertically projecting barrier plates such as 180,182, 184 which serve to provide distinct compartments for receipt of theflowable granular material. Finally, an anchor spade 190 projectsgenerally angularly downwardly into the underlying sand 192 to securethe structure in the desired orientation. Similar elements are providedin units 126, 128 and 130. It will be noted that unit 130 does not havea ballast section, but rather has a vertically projecting barrier plate192. It also provides a downwardly projecting anchor 194 which hasopenings 196, 198, 200, as well as similar downwardly projecting anchors202, 204 with openings, respectively 206, 210, 212, which permitdrainage of water outwardly toward the open body as indicated by arrowH.

In a preferred embodiment, the upwardly sloped ramps, except for theelongated sand-delivering slots such as 174, 176, 178 will besubstantially continuous and preferably be made from a material selectedfrom the group consisting of plastics, organic materials and protectedmetallic materials, such as metals covered or enclosed within a barriermaterial, such as a resinous plastic, for example.

It will be appreciated that the height of the opening between theundersurface of the next adjacent vertically spaced unit and theuppermost portion of the inclined upwardly sloping ramp will be about 1to 3 inches and preferably about ¼ to ½ inch in order to facilitateefficient receipt of the waves.

FIG. 6 shows a more detailed view of an elongated ballast element 220which has a barrier plate 222. The ballast, which is preferably sealedwithin the structure, can be any suitable material adequate tomaintaining the erosion control unit in place on the beach surface.

Referring to FIG. 7, the interaction of adjacent units and valve effectwill be considered. In this embodiment, a first wave deflection ramp 230is oriented inwardly and upwardly toward the shore in a unit (only aportion which is shown) having a generally horizontal surface 232 toreceive a portion of the sand with an appropriate ballast material 234contained within the ballast element. Similarly, a wave deflection ramp240 has ballast 242 and a generally horizontal surface 244 provided withan elongated slot 246 and a generally vertical barrier plate 248 with aquantity of flowable granular material such as sand 250 supported onhorizontal surface 244. It will be appreciated that as the waves move inthe direction shown by arrow I, there is a change in velocity of thewave resulting in a portion of the flowable granular material, such assand, being deposited on the surface of portion 244 with elongated slot246 serving to permit the sand to drop into the underlying structurewhen the quantity of sand 250 reaches a predetermined level. It will beappreciated that the elements described in FIGS. 5 through 7 and inportions of the remaining figures have their elongated direction intothe page of the drawing and may be whatever desired length will bestaccomplish the beach erosion resisting objective.

It is preferred that the wave deflection ramp such as 240 and 230 havean included lesser angle with respect to the horizontal base portion ofthe unit 244, 232, respectively, of about 10 to 40°. The ballastmaterial should have a specific gravity greater than one. The ballastmay be metal pellets enclosed in plastic, for example.

It will be appreciated that the size of the fluid openings which mayhave a height H from the undersurface such as surface 260 of ballast 262shown in FIG. 8 to the uppermost surface of ballast 263 or the surfacegap H¹ between the lower surface 264 of ballast 262 and the uppermostsurface of ballast 268 which provides a fluid opening for flow of wavesin the directions of arrows J and K, respectively. This thereby allows aportion of the wave optimum in size to enter the structure so that thesuspended flowable granular material such as sand can be trapped anddeposited on the beach surface. In the form shown in FIG. 5, forexample, the lowermost ballast 128 is closest to the approaching waveand, in stepwise manner, the uppermost ballast 120 is farthest therefromto provide the desired input flow of the wave.

In FIG. 9, there is shown an end view of the elongated horizontal slotssuch as 280, 282, 284, 286, 288, 290 to permit progressive downward flowof the material from the uppermost spaced vertical unit 294 through theintermediate unit 296 to the lower unit 298 to thereby facilitategravitational redeposit of this sand on the beach.

FIG. 10 shows an end view of a portion of a unit 300 which hasupstanding barrier walls 302, 304 and an anchor portion 306 whichextends into the sand 308 to anchor the structure in the desiredgenerally horizontal position within the water which overlies the sand308. In the portion of unit 310 shown, the anchor 312, as well as thehorizontal portion 314, are submerged below sand level. If desired, theunits may be placed other than perpendicular to the beach or shorelineto accommodate the anticipated angle of arrival of waves.

It will be appreciated that as sand is deposited as shown in FIG. 10,the deposited sand can lift the structural units above the initialposition so as to provide for ongoing efficient removal of sand from theincoming waves.

It will be appreciated that another function of the anchors such as 308,312 is to resist undesired horizontal rotation of the structure.Further, additional ballast may be added at the outermost portions ofthe unit, if desired, to resist undesired movement.

In this embodiment the combination of the flow control valves, thehorizontal slots, the vertically spaced relationship between units andthe anchors are such that the force of the incoming wave is not opposed,but rather utilized to transport and deposit the flowable granularmaterial such as sand in a useful manner to reestablish the beach. Thecapture and retention of the sand is facilitated by the upwardlyprojecting elongated vertical barrier plates and the elongatedhorizontal slots for vertically downward gravitational transfer of thesand. It will be appreciated that the structure both restores the beachand resists further erosion of the sand.

Referring to FIG. 11, there is shown a cross-section taken through 11-11of FIG. 5 which shows a form of structure as viewed from the directionof which the wave is approaching. The structure has a plurality ofelongated units which, in the form shown, extend generally parallel tothe beach with the entry spaces for the waves being shown as gaps 350,352, 354, 356. Water drainage slots such as shown in element 138 in FIG.5 facilitate discharge of water in the direction coming out of the pageto facilitate removal from the stored sand.

Referring to FIG. 12, which is in a view taken similar to that throughSection 12-12 of FIG. 5, wherein the plurality of vertically projectingbarrier walls 410, 412, 414, 416 have adjacent horizontal slots 420,422, 424, 426, respectively, to facilitate sand moving downwardly fromadjacent the positions where the vertically upwardly projecting wallsappear.

Referring to FIG. 13, there is shown a top plan view through 13-13 ofFIG. 1 employing different reference numerals for clarity ofpresentation. FIG. 13 illustrates in top plan view modular aspects ofthe beach retention and replenishment embodiment. The wavy line to theleft of section 442 is toward the beach and the wavy line on the top ofFIG. 13 is oriented generally angularly with respect to the beach. Thesolid line to the right of section 430 is adjacent the direction fromwhich the waves will arrive. The units 430, 432, 434, 436, 438, 440, and442 may contain the elements described in connection with FIGS. 5-12 andmay be upwardly stepped from unit 430 to unit 442. The number of units430-442 (even numbers only) and the length of the units 430-442 (evennumbers only) may vary according to the specific design.

It will be appreciated that the present invention has provided means forestablishing a first embodiment wherein a flowable granular materialvalve without requiring movable parts facilitates flow in one directionthrough the valve passageway and resists flow in the opposite direction.In addition, in another embodiment, an efficient economical retainingwall having passageways so configurated with respect to the normal angleof repose of an adjacent of pile of flowable granular material as toresist undesired excessive forces against the wall. Finally, in anotherembodiment, the beach renourishment construction is provided whichfacilitates allowing wave flow, removing flowable granular material,such as sand, therefrom and retaining such sand while returning thewater to the open body of water.

Whereas particular embodiments of the invention have been describedherein for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details may be made withoutdeparting from the invention, as defined in the appended claims.

1. A valve for permitting passage of a flowable granular material in afirst direction while resisting such flow in a second directioncomprising a valve housing defining a passageway for flow of saidmaterial therethrough, said passageway having an upperpassageway-defining surface, lower passageway-defining surface and firstand second passageway-defining surfaces disposed between said upper andlower passageway-defining surfaces, and said upper and lowerpassageway-defining surfaces diverging.
 2. The valve of claim 1including said upper and lower surfaces diverging in said seconddirection and converging in said first direction.
 3. The valve of claim1 including said upper and lower surfaces diverging in said firstdirection and converging in said second direction.
 4. The valve of claim1 including said upper and lower surfaces being generally planar.
 5. Thevalve of claim 2 including said upper and lower surfaces structured toprovide an angle of repose of said flowable granular material of about20 to 45°.
 6. The valve of claim 5 including said upper and lowersurfaces structured to provide an angle of repose of said flowablegranular material of about 30 to 40°.
 7. The valve of claim 2 includingsaid lower passageway-defining surface being substantially horizontaland said upper passageway-defining surface being angularly disposed withrespect thereto.
 8. The valve of claim 3 including said upperpassageway-defining surface being substantially horizontal.
 9. The valveof claim 8 including said lower passageway-defining surface beingangularly disposed with respect to said upper passageway-definingsurface.
 10. The valve of claim 1 including said upper and lowerpassageway-defining walls having sufficient width to resist undesiredflow of said material out of said second direction.
 11. The valve ofclaim 1 including said lower passage-way defining wall having a smallerwidth than said upper passageway-defining wall.
 12. The valve of claim 1including at least one of said upper passageway-defining walls and saidlower passageway-defining walls being non-planar.
 13. A retaining wallfor a flowable granular material comprising a hill composed of saidflowable granular material, a wall positioned along a lower portion ofsaid hill and having a front face and a rear face, said hill beingsupported at least partially by said wall, said wall having a heightgreater than the adjacent portion of said hill disposed adjacent saidrear face, said wall being provided with a plurality of generallyhorizontal passageways such that the angle of repose of said materialwithin said passageways will permit said material to flow toward thefront surface of said passageways without substantial discharge of saidmaterial therefrom, while under changed circumstances will effect areduction in the force against the rear face of said wall by permittingdischarge of said material therethrough.
 14. The retaining wall for aflowable granular material of claim 13 including said elongatedpassageways having a length greater than their height.
 15. The retainingwall for a flowable granular material of claim 14 including saidpassageways having a height-to-width ratio of about 3 to
 1. 16. Theretaining wall for a flowable granular material of claim 13 includingabout 70 to 90% of the exposed wall rear surface being occupied by saidpassageways.
 17. The retaining wall for a flowable granular material ofclaim 15 including said passageways being of sufficient size to provideoverpressure relief to thereby resist undesired displacement of saidwall responsive to increased pressures thereon from said flowablegranular material.
 18. The retaining wall for a flowable granularmaterial of claim 16 including said wall having a height greater thanthe height of the adjacent said flowable granular material disposedadjacent the rear of said wall.
 19. The retaining wall for a flowablegranular material of claim 13 including said generally horizontalpassageways extending continuously from said wall rear face to said wallfront face.
 20. The retaining wall for a flowable granular material ofclaim 13 including at least some of said passageways being disposed atdifferent elevations on said wall from other said passageways.
 21. Abeach erosion control system for removing sand from incoming watercomprising a plurality of generally horizontally oriented, verticallyspaced separation units having a wave-deflecting ramp for receiving saidsand containing water thereover, a plurality of elongated, generallyvertically oriented, relatively spaced barrier plates oriented generallyparallel to each other and spaced from said wave deflection ramp, aplurality of elongated slots for facilitating downward transfer of sand,and at least one anchor for securing said unit to said sand.
 22. Thebeach erosion control system of claim 21 including a said elongated slotbeing disposed between a pair of said barrier plates.
 23. The beacherosion control system of claim 22 including at least some of saidanchors having openings for facilitating drainage of water therethroughto enhance separation of said sand therefrom.
 24. The beach erosioncontrol system of claim 21 including said wave deflection ramps havingballast therein.
 25. The beach erosion control system of claim 21including said barrier plates having a height of about ¼ to ½ inch. 26.The beach erosion control system of claim 21 including the spacingbetween adjacent pairs of said barrier plates being about ½ to 1 inch.27. The beach erosion control system of claim 21 including each saidelongated slot being disposed adjacent to a said barrier plate.
 28. Thebeach erosion control system of claim 21 including said units beingcomposed of materials selected from the group consisting of plastics,organic materials and protected metallic materials.
 29. The beacherosion control system of claim 21 including the undersurface of saidunits being substantially flat except for said anchors.
 30. The beacherosion control system of claim 29 including the spacing between thesaid horizontal undersurface of said unit excluding said anchor and theuppermost portion of the barrier plates of the next underlying said unitbeing about 1 to 3 inches.
 31. The beach erosion control system of claim21 including adjacent said barrier plates serving to receive sandtherebetween.
 32. The beach erosion control system of claim 21 includingsaid units structured to facilitate passage of sand containing water inincoming waves of said water, but resisting outward flow thereof awayfrom said beach.
 33. The valve of claim 1 including said wave deflectionramp having an angularly upwardly and inwardly upper surface forchanneling incoming waves between said surface and the undersurface ofthe next adjacent vertically spaced said separation unit.
 34. The valveof claim 33 including said water deflecting ramp having ballastcontained therein.
 35. The valve of claim 33 including said wavedeflection ramp having a generally triangular cross-sectionalillustration.
 36. The beach erosion control system of claim 21 includingsaid vertically spaced separation units being provided in staggeredrelationship with a lower unit extending farther outwardly from saidbeach than the next adjacent vertical unit.
 37. The beach erosioncontrol system of claim 30 including said spacing being about ⅛ to 1inch.